FreeCAD Assistance

[hilt_ctn]

Trying to teach myself FreeCAD and I'm coming up against an inconsistency with padding. Sometimes I get it right. Sometimes it ends up like what follows. I just can't put my finger on what I'm occasionally doing wrong. Take the following example. I'm only adding shapes with random sizes and dragging them around to display the issue. No constraints, external geometries etc. i.e. nothing fancy

Pic 1
I added a circle and added a triangle. The pads up nicely

Pic 2
Edited the sketch and added a slot shape on the left hand side. Only the circle the pads

Pic 3
Edited the sketch again and added a slot on the right site. Now nothing pads at all

Pic 4
New attempt. Pads out correctly. Aside from the arm angles being different, I did what to my mind was exactly the same process

Any idea what I'm doing wrong for pics 2 and 3 ? If this were a Powerpoint slide, I feel like I'm missing the " Bring to front" option

I also managed to get out a complete object ( Overengineered Cookie Cutter ). This is to show that I have done some reading/watching and did some more complicated stuff. But it's bugging me that I can't consistently get a "full pad" per the above. I basically have to get lucky with a Pic 4 scenario before I can move on.

@Tinuva

 

[saor]

Don't use freecad but in pic 2 and 3 you have 3 overlapping shapes and the software might not know what you want at those intersections. All your other images you only have two overlapping shapes and it works.

So either trim those lines back to create a single entity....


or alternatively just do those body parts separately rather than trying to stick it all in one sketch. I can't see any reason why you need to do everything at once like that.

 

[Tinuva]

So I think the first important thing to know is, you doing this in "part" workbench or the "part design" workbench.

They are doing the same thing, but different.
Part design = work with solids
Part = work with surfaces

In Part workbench, you need to fuse objects together and convert to a solid. Thats the order, to keep it consistent.
The other thing, you want to have your shapes fully constrained. Maybe that is what is missing. First fully constrain the objects, then extrude (read, pad) them.

Videos that I found helpful on what you doing:
Lesson 5 | Part vs Part Design which one to choose? Basic Beginners FreeCAD v1 / 0.22
Lesson 6 | Real World to Digital. Simple Single Plane Extrudes

 

[Tinuva]

Don't use freecad but in pic 2 and 3 you have 3 overlapping shapes and the software might no know what you want at those intersections. All your other images you only have two overlapping shapes and it works.

So either trim those lines back to create a single entity....
View attachment 1787636

or alternatively just do those body parts separately rather than trying to stick it all in one sketch. I can't see any reason why you need to do everything at once like that.

Yeah I agree, I think he needs to ensure the sketches are fully constrained. Freecad will show an error for this.

 

[spiff]

@hilt_ctn

do you have the latest FC version?

I use catia and prefer doing 1 sketch with as much detail in as posible to create 1 closed profile before I pad or extrude. If that's not possible then I trim where needed, then pad.

you can also use the sketch and offset to the inside by the CC thickness then pad it.

 

[saor]

or alternatively just do those body parts separately

Much easier to do the features separately, especially for something like this.

 

[hilt_ctn]

A big thank you to all who responded. Learning quickly now

For the overengineered cookie cutter, I have several object overlaps and they came out ok. But I think that's what confused my little noggin'. i.e. it worked previously, why wouldn't it work again ? A true rookie at work here

Lesson 1 - Separate into sketches more often to give greater control.
Lesson 2 - Trim back the overlaps

I've given these a bash and it immediately solved my issue. You all rock !

 

[hilt_ctn]

So I think the first important thing to know is, you doing this in "part" workbench or the "part design" workbench.

They are doing the same thing, but different.
Part design = work with solids
Part = work with surfaces

In Part workbench, you need to fuse objects together and convert to a solid. Thats the order, to keep it consistent.
The other thing, you want to have your shapes fully constrained. Maybe that is what is missing. First fully constrain the objects, then extrude (read, pad) them.

Videos that I found helpful on what you doing:
Lesson 5 | Part vs Part Design which one to choose? Basic Beginners FreeCAD v1 / 0.22
Lesson 6 | Real World to Digital. Simple Single Plane Extrudes

I was working in Part at the time

 

[hilt_ctn]

@hilt_ctn

do you have the latest FC version?

I use catia and prefer doing 1 sketch with as much detail in as posible to create 1 closed profile before I pad or extrude. If that's not possible then I trim where needed, then pad.

you can also use the sketch and offset to the inside by the CC thickness then pad it.

Yes indeed. I caught it on a YouTube vid and thought I'd give it go. My wife, a teacher, saw me fiddling and now I'm mocking up more dough / cookie cutters than I can count !

Will have a look at Catia when I'm brave enough. This is my first jaunt into the 3D design world. Never done anything like it before so the learning curve feels like a vertical cliff face !

 

[hilt_ctn]

So I think the first important thing to know is, you doing this in "part" workbench or the "part design" workbench.

They are doing the same thing, but different.
Part design = work with solids
Part = work with surfaces

In Part workbench, you need to fuse objects together and convert to a solid. Thats the order, to keep it consistent.
The other thing, you want to have your shapes fully constrained. Maybe that is what is missing. First fully constrain the objects, then extrude (read, pad) them.

Videos that I found helpful on what you doing:
Lesson 5 | Part vs Part Design which one to choose? Basic Beginners FreeCAD v1 / 0.22
Lesson 6 | Real World to Digital. Simple Single Plane Extrudes

Will definitely have a look at these

 

[Tinuva]

Will definitely have a look at these

Thy Playlist has excellent videos in it

 

[spiff]

Yes indeed. I caught it on a YouTube vid and thought I'd give it go. My wife, a teacher, saw me fiddling and now I'm mocking up more dough / cookie cutters than I can count !

Will have a look at Catia when I'm brave enough. This is my first jaunt into the 3D design world. Never done anything like it before so the learning curve feels like a vertical cliff face !

keep at it. youtube is an amazing resource.

freecad is like a cross between solidworks / catia, not that difficult to learn. My first forray in CAD back in the 90's was with CADDS4x software which ran on a Sun Spark workstation - Unix based, not easy to learn.

I've been doing CADCAM / 3d designing since the early 90's. now I teach CADCAM & CNC advanced machining at an engineering college. call me if you need help or have any questions etc.

 

[Tinuva]

And this is why I liked that you created a thread instead of PM. Now we can do a freecad design community thread

 

[AntennaMan]

Freecad 1.0 is also a major step forward.

 

[Tinuva]

@hilt_ctn

Here, I am editing an existing .stl file. This is after I did a bunch of things to make it easier to edit etc. But at this point, I am now doing a modification I want. You can see, in the sketch, on the right (I moved my tasks there), it shows that the sketch is fully constrained. Now, if I pad or pocket, it always ends up doing the same thing.

So the fully constrained step, I learned from a guy while learning Fusion360, he kept going on and on and on and on forever, about how important the sketch is and that it must be fully constrained. So that lesson stayed with me while moving to freecad.

 

[PowerFactor]

@Tinuva what does the constraint limit in the drawing?

 

[Tinuva]

@Tinuva what does the constraint limit in the drawing?

Slightly better image.

On the right side, in the task, you can see it lists 6 constraints, 3 per circle.

So per circle:

1. Constraint 1 is the size of the circle is constrained to size 17mm
2. Constraint 2 is, I am not sure, but that was added automatically when I created the circle. Oh I figured it out. If you start the circle center on the line, eg in this case what looks like the X axis of this sketch, it automatically adds this. I am sure there i a name, but I can't find it on the toolbar to confirm the name of this constraint.
3. Constraint 3 is the distance between the center of the circle, and the center of the face of the solid object, I started the sketch on. so 12mm.

 

[Tinuva]

My latest design. Still super basic, but will work well for guy ropes on a long pole.

What annoyed me with this one is, the 4 things that stand out, I could use a polar pattern to replicate a single one into four, but the hole didn't replicate with it. So had to do that 4 times. Must be missing something when I did that. But using variables, was fairly quick to manual replicate and can still update sizes in a single place with a variable.

 

[spiff]

My latest design. Still super basic, but will work well for guy ropes on a long pole.

What annoyed me with this one is, the 4 things that stand out, I could use a polar pattern to replicate a single one into four, but the hole didn't replicate with it. So had to do that 4 times. Must be missing something when I did that. But using variables, was fairly quick to manual replicate and can still update sizes in a single place with a variable.

View attachment 1788991

This is what I do in catia / solidworks.

Try selecting the holes and the tags together when you polar pattern.

Also when you make holes of the same size. Dimension one hole and make the others equal to the dimensioned hole.

That way all holes of equal diameter are driven by one master hole. Makes editing or updating easier.

 

[RedViking]

Is fusion 360 still free for hobbyists? Works also great for Cookie cutters and if you keep the history in tact of the time line you can make adjustments and everything else will update as well.